The present invention relates to the field of intravascular devices, and more particularly to a guide wire suitable for procedures such as angioplasty and/or stent deployment, and the like.
In percutaneous transluminal coronary angioplasty (PTCA) procedures a guiding catheter is first advanced in the patient""s vasculature until the distal tip of the guiding catheter is seated in the ostium of a desired coronary artery. A guide wire is first advanced out of the distal end of the guiding catheter into the patient""s coronary artery until the distal end of the guide wire crosses a lesion to be dilated. A dilatation catheter, having an inflatable balloon on the distal portion thereof, is advanced into the patient""s coronary anatomy over the previously introduced guide wire until the balloon of the dilatation catheter is properly positioned across the lesion. Once properly positioned, the dilatation balloon is inflated with inflation fluid one or more times to a predetermined size at relatively high pressures so that the stenosis is compressed against the arterial wall and the wall expanded to open up the vascular passageway. Generally, the inflated diameter of the balloon is approximately the same diameter as the native diameter of the body lumen being dilated so as to complete the dilatation but not overexpand the artery wall. After the balloon is finally deflated, blood flow resumes through the dilated artery and the dilatation catheter and the guide wire can be removed therefrom.
After such angioplasty procedures, there may be restenosis of the artery, i.e. reformation of the arterial blockage, which necessitates either another angioplasty procedure or some other method of repairing or strengthening the dilated area. To reduce the restenosis rate of angioplasty alone and to strengthen the dilated area, physicians now typically implant an intravascular prosthesis, generally called a stent, inside the artery at the site of the lesion. Stents may also be used to repair vessels having an intimal flap or dissection or to generally strengthen a weakened section of a vessel or to maintain its patency.
Stents are usually delivered to a desired location within a coronary artery in a contracted condition on a balloon of a catheter, which is very similar in many respects to a balloon angioplasty catheter, and the stent is expanded within the patient""s artery to a larger diameter by inflating the balloon. After stent deployment, the balloon is deflated to facilitate removal of the catheter and the expanded stent is left in place within the artery at the site of the dilated lesion. See, for example, U.S. Pat. No. 5,507,768 (Lau et al.) and U.S. Pat. No. 5,458,615 (Klemm et al.), which are incorporated herein by reference. Instead of first using one balloon catheter to dilate the body lumen and a second balloon catheter to deploy the stent after the dilatation, the stent may be mounted on a balloon catheter and deployed at the same time the balloon is inflated to dilate the stenotic region.
In both of these procedures the physician has to make an estimate of the length of the stenotic region which is to be dilated or into which a stent is to be deployed in order to assess the length of the balloon to be used or the length of the stent to be deployed. Heretofore, it has been suggested to provide a variety of markers on the distal portion of the guide wire and/or catheters in order to measure the length of a stenosis or other anatomical region.
Many of these prior efforts involve providing various spacings between multiple radiopaque markers on the distal portion of the guide wire to allow the physician to make the length determination fluoroscopically with the guide wire in position within the artery and the markers traversing the stenotic region. For example, conventional approaches include using the helical coil commonly found at the distal end of the guide wire to include spaced apart radiopaque rings. Another approach is attaching radiopaque bands directly to the outside diameter of the guide wire core. The radiopaque bands are mounted to the core by adhesives or by use of shrink wrap covering the bands. Sometimes polymer sleeves are positioned in between the bands to function as spacers. However, the thick bands with shrink wrap would change the outside diameter of the core, and/or the stiffness of the wire. Accordingly, there is presently a need for an improved radiopaque marker arrangement for use with an intracorporeal device such as a guide wire and the like.
The present invention is generally directed to an intracorporeal device, such as a guide wire, for measuring a length of an anatomical feature or the distance between anatomical features within a patient""s body, such as the length of stenosis within a patient""s coronary arteries.
In one embodiment, the intracorporeal device comprises an elongated, solid core member having a proximal core section and a distal core section having at least one constant diameter portion and at least one tapered portion which tapers in the distal direction to smaller transverse dimensions; a continuous polymer sleeve secured to the distal core section having a plurality of radiopaque spaced apart marker edges embedded into the sleeve; and a flexible body disposed about and secured to the distal core section.
The intracorporeal device embodying features of the invention has a plurality of spaced apart marker edges or other location indicia on the distal portion of the device. The markers are observable (e.g., fluoroscopically) by the physician or other personnel while inside a patient during a procedure. In particular, the intracorporeal device is positioned within the patient""s body with one of the marker edges being placed at or adjacent to a first intracorporeal location. The distance between the first intracorporeal location and a second intracorporeal location can then be determined by counting the marker edges and knowing the distance between the marker edges.
In one embodiment of the invention directed to guide wires, the polymer sleeve having a plurality of spaced apart marker sleeves is secured to a tapered or constant diameter portion of the distal core section. The flexible body includes a helical coil also at the distal core section of the guide wire. The marker containing sleeve may be positioned between coil segments, under coil segments, or at the end of a coil segment. The sleeve maybe heat shrunk onto the distal core section or it may be secured by adhesive or other suitable ways.
The marker containing sleeve may take several forms. In one form, the radiopaque marker or markers are provided on the exterior of a polymer sleeve. The markers may be applied in a variety of ways but plating is presently preferred. The entire exterior of the sleeve may be plated with a radiopaque material, and after plating the marker edges are formed by removing some of the plated material. Alternatively, a masking material may be placed on the exterior of the polymer sleeve to expose only those areas on the exterior which are to be plated. After the plating, the masking material may be removed.
In another embodiment of the marker containing sleeve, the marker or markers are embedded within the wall forming the polymer sleeve. The marker containing sleeve may be formed by disposing or otherwise applying an inner polymer layer onto the exterior of a mandrel of a desired shape. Individual ribbons of radiopaque material is wrapped around the inner polymer layer while still mounted on the mandrel. The continuous ribbon of radiopaque material is helically wrapped about the inner layer with a space between the individual turns to provide an appearance of a plurality of marker edges on one side of the sleeve. An outer polymer layer is applied to the partially completed sleeve on the mandrel to complete the sleeve construction. The inner and outer polymer layers may be heat shrunk, fused, or adhesively bonded to each other. If desired, the portion of the distal core section on which the sleeve is to be secured may be used as a mandrel so that the sleeve can be formed in situ.
In addition, the marker containing sleeve may be magnetic resonance imaging (xe2x80x9cMRIxe2x80x9d) compatible. There would be no change in the overall construction of the marker containing sleeve, but materials in addition to common radiopaque marker materials would be needed, such as, NiTi and ternary alloys thereof. Paramagnetic materials such as gadolinium, chromium, nickel, copper, iron and manganese, and superparamagnetic materials could also be added for compatibility with MRI.
There are still other radiopaque materials that if added to the presently described marker containing sleeve would permit it to be MRI compatible. These radiopaque materials include, but are not limited to, platinum, iridium, gold, barium, bismuth, and other radiodense salts.
The location of the marker containing polymer sleeve on the core member depends upon the structure and use of the intracorporeal device, and particularly in the case where the intracorporeal device is a guide wire. To ensure that the distal position of the guide wire is not lost by movement of the guide wire during anatomical measurement, it is preferred to position the marker containing sleeve on the distal core section at a location spaced proximal to the distal end of the guide wire, preferably about 1 cm to about 20 cm, and more likely 3 to 5 cm as measured from the leading edge of the sleeve. The marker sleeve may be heat shrunk onto the core member, or secured to the core member in other suitable ways such as by adhesives and the like.
The guide wire or other intracorporeal device embodying features of the invention may be used in an intracorporeal procedure by introducing the distal portion of the guide wire or other device into the patient""s body by a suitable procedure and advanced within the patient""s body until the marker sleeve on the guide wire or other device is disposed at a desired intracorporeal location. The physician or other operator can fluoroscopically detect the markers on the marker sleeve and measure a length of anatomy by counting the number of marker edges and knowing the distance between the marker edges.
As a result, the use of the present invention marker containing polymer sleeve provides accurate placement of the marker edges for intracorporeal anatomical measurement with essentially no significant increase in the profile of the guide wire or other intracorporeal device. These and other advantages of the invention will be come more apparent from the following detailed description and the accompanying exemplary drawings.